Black-headed gulls paddling

I've written about foot-paddling for worms on wet grass in Herring Gulls and Common Gulls in this blog before. My local park has flooded in the last few weeks and Black-headed Gulls have moved in, enjoying the flushes, which bring up a lot of worms. Black-headed Gulls foot-paddle in water, but apparently they don't do it on wet grass like other gulls (but see the clips by Ralph Hancock in the comments). In an article on foot paddling in gulls Niko Tinbergen speculated that the reason could be that Black-headed gulls are not heavy enough to produce the vibrations on the ground that stimulate the migration of worms to the surface.
I had never seen Black-headed Gulls paddling on water before. This morning there were at least 30 Black-headed gulls and I noticed a one briefly paddling on shallow water, and checking in front of its feet. A young gull came along and when at the same spot it started paddling too. I managed a short clip of it.

After a while one of the young ones got a worm, unclear if due to the paddling. Walking around the pools on areas where the gulls don't go by the road it was apparent that there were a lot of dead (drowned?) worms. I think that's what the gulls are after in the flood. The Herring gulls were also energetically pulling grass and leaves and soil from the shallow puddles to expose food.

More information
Tinbergen, N. Foot-paddling in gulls. Br. Birds 55, 117 (1962)

Loafing gulls

 Gulls spend a good portion of their days doing what is known as 'loafing', in open areas of good visibility: playing fields, beaches, but also on water and on ice in frozen lakes, the same sites are chosen year on year. These loafing areas are different from night roosting sites. At loafing sites gulls appear relaxed: some sleep - head under wing - others sit or stand watching around, others preen. Immatures may play with objects such as sticks or leaves. Loafing areas are common areas, and tend to be quiet, with little or no squabbling or aggressive behaviour, often with several species mixing in the same area. Individuals come and go, commuting to their feeding areas, unless a disturbance provokes a sudden communal flight. On the coast, the number of individuals in a loafing area follows a tidal cycle - as low tides expose food resources the gulls move away the loafing area to feed- and also time of the year. Tidal influence in sleeping is highly prevalent in wading birds, which strongly depend on exposed shores for feeding. A study in Herring Gulls suggest that they have a dual sleeping pattern, with the proportion of sleeping gulls peaking at midnight and at midday. This may be a common pattern with urban gulls or away from the coast, where food is less related to tidal fluctuations.

A mixed flock of Black-headed gulls, Common Gulls and Herring gulls loafing on a rise on a local park.

Loafing gulls allow good opportunities to check individuals for plastic rings, as shown by this preening Common Gull.

A group of Common Gulls loafing on ice on a frozen pond of (16/1/2013)

More information
Shandelle M. Henson, James L. Hayward, Christina M. Burden, Clara J. Logan and Joseph G. Galusha. 2004. Predicting Dynamics of Aggregate Loafing Behavior in Glaucous-Winged Gulls (Larus glaucescens) at a Washington Colony. Auk 121, 380–390.

Cooke, F. and Ross, R. K. 1972. Diurnal and Seasonal Activities of a Post-Breeding Population of Gulls in Southeastern Ontario. Wilson Bull. 84, 164–172.

Galusha, J. G., JR and Amlaner, C. J., JR. 2008. The effects of diurnal and tidal periodicities in the numbers and activities of Herring Gulls, Larus argentatus, in a colony. Ibis 120, 322–328.

Gulls playing helter skelter?

Do birds play? You have probably seen videos of crows sliding down snow and rolling down on car windscreens, or heard of the Australian black swans that enjoy surfing. These cases, and many others documented for a long time, are hard to explain in utilitarian terms (no feeding, or mating or predator avoidance is involved), it appears purposeless, and seem most fitting to actual play. Play behaviour, often solitary, some times involving objects, but also social, has been described in ten orders of birds including corvids, raptors and parrots amongst others. Some of this behaviour involve play flying, or flying in aerobatic ways. This afternoon, in the first mild sunny day of spring, thermals developed over the park, and a large mixed flock of gulls - Herring, Common, Lesser Black backed and at least a black-headed, later joined by a Carrion Crow - started to soar higher and higher, I could barely see them as they circled. My camera decided to run out of battery run out just at the same time (the photo above is the flock flying high this mid February).
 Then I noticed some gulls tumbling down. Not just gliding, but actually flipping over and going on their backs as they descended. Two of them seemed to be flying together, making a downward double spiral, opposite each other, occasionally tumbling. The Carrion Crow also dropped height by closing its wings as if enjoying the feeling of being kept up by the thermal. It was an exhilarating spectacle to watch, and the gulls gave the impression to be having a good time.

City scavengers

We humans can make a mess. Bins left open or toppled over, the remains of takeaways eaten on the street thrown to the pavement. It is not a pretty sight, but it means extra feeding opportunities for some. Birds take advantage of their surroundings: they eat the berries, buds, and flowers of the trees we plant in our gardens, they do reward our love for them feeding on delicacies on the bird table, but they will also eat our rubbish. Today, a Carrion Crow (top shot) searched for tidbits under a rubbish bag using that lovely crow technique of delicately picking 'things' and moving them aside. They do the same when feeding on leaf litter,  and it is quite different to the energetic, almost full body technique for the same effect used by Blackbirds. The Carrion Crows and Blackbirds often feed at the back of a row of flats, where bins are often left open and bin bags on the ground. My favourite sighting of a scavenging crow was one strutting on a pavement with a large sausage held across its bill, a pity I was driving at the time! Seagulls are supreme city scavengers too, with their bouncy, manoeuvrable flight, Black-headed Gulls are able to avoid the passing traffic - as they will avoid waves out at sea - to deftly dip in the middle of the road to pick items from in between cars.

Snow bonanza for a male blackbird...

...and a female too

Even Robins enjoy takeaway pizza

Black-Headed Gull on the lookout for feeding opportunities

Changing Heads

The first Black-headed gulls honouring their names have now appeared. The dark head is their summer attire and this makes them much easier to tell apart from the white headed, and very common, Common Gulls. This winter I have been testing my ID skills on flying city gulls. Black-Headed gulls are much more keen to pick scraps from the ground in busy streets and their flight is quite bouncy. The white front of their wing primaries can also be very obvious. I found the almost completely molted individual above in a local park on Valentine's day, and later, in a flock, only a couple of individuals have completed the molt, while most are on their winter plumage.